Many types of bags have been designed for specific uses. Photographers, in particular, require bags which are adapted to carry photographic equipment and supplies in a manner that will protect that equipment and supplies. In some cases, particularly in the field of nature photography and the like, rather large amounts of equipment are carried in significantly large bags. In view of the size of the bags and the amount of the equipment carried, such bags are often fitted with harnesses so that the bags may be carried like a backpack. In other cases, where relatively smaller amounts of equipment are carried, the bag may be of a more convenient size but is often equipped with a strap or harness in order that the bag may be carried by means of a strap which would be looped over one shoulder of the photographer or passed around the waist.
Quite apart from the photography field, there are other specialized bags of a similar nature. Outdoors persons generally are familiar with backpacks which may be used to carry all manner of camping supplies or other supplies. There is also a wide range of smaller bags carried in shoulder straps and the like for carrying other than photographic supplies.
One common feature of these types of bags is that they are carried in all kinds of weather. Such bags during good weather conditions provide sufficient protection for the goods carried within the bags. However, in inclement weather such bags may leak water or admit fine dust.
Most bags are arranged with some type of openable flap having closure means which extend around the upper portion of the bag. In addition, the bag may have one or more compartments each of which is accessible through a hinged flap having closure means. The usual type of closure is a zipper. Other types of closures such as hook-and-loop materials such as that sold under the trade mark VELCRO may be used. Snap fasteners and the like may also be used as appropriate.
It is usually desired that the bags be manufactured from lightweight but strong material. To this end, many bags are now manufactured from nylon products which are soft sided but still give the required protection by means of inserts or the like which provide against crushing of the equipment carried in the bag.
When the traditional bag is carried in inclement weather there arises the danger of leakage through the bag material itself or through the closures. As the bags are often equipped with a number of different pockets for various size articles, there are often a number of such closures, and some or all of those closures may leak.